The apparatus used and the methods employed in the radiographic examination of the breast are well known in the art. A preferred technique and apparatus are described in H. J. Lasky U.S. Pat. No. 3,578,971, and the entire disclosure of that patent is hereby incorporated herein by reference, to the extent it is not inconsistent herewith.
The present invention finds special utility as a test standard providing, in mammograms, visual indicia for quickly and effectively judging the quality of mammograms.
It has become an established and wide-spread medical practice to conduct such X-ray tests on female subjects to determine whether any of the subjects suffers from breast cancer or whether any of the radiologically-examined tissues evidences other abnormal conditions. Since the examinations themselves are carried out by different medical practitioners and by X-ray technicians using various different types of X-ray equipment and recording media, there has been a real problem in establishing the extent to which the X-ray pictures produced would be expected reliably to show the true condition of the tissue examined. The problem described is aggravated by the fact that many different "reviewers" may be involved in the overall investigation.
Breast phantoms which are designed to "simulate" the breast have been used to test the capability of the X-ray system, with respect to resolution and contrast. However, this approach has not proven widely applicable, is costly and not widely accepted.
It has become undeniably evident that it is exceedingly difficult, relying on visual examination of a given X-ray image, and nothing more, to know with any degree of certainty whether the image represents a high-quality and, accordingly, a reliable visual representation of the existing field or, whether the plate is of such caliber as not to merit unquestioned reliance. If the image quality is inadequate to demonstrate tiny particles of calcium, often the only sign of an early cancer, the interpreter would not know that they were present. A third party X-ray expert or trained radiologist independently examining the plate would not have an objective awareness or perspective as to the technical deficiency of the radiograph itself.
While the type of problem indicated may not exist in those instances in which a tumor or cancerous tissue is well developed and, thus, clearly visible to all, one will appreciate that in the very early stages of the development of such tissue abnormalities, a reliable diagnosis based upon an examination of X-ray plates is much more difficult. Yet early diagnosis is a very important element in arresting and in effectively treating cancerous tissues and tissues which exhibit conditions precursory to cancer, particularly breast cancer.
It is, accordingly, the aim of the present invention to overcome the inadequacies and the shortcomings of prior techniques and devices and to provide a simple and effective apparatus and method by which a person examining a mammographic X-ray film or plate may reliably know, from a visual examination of the developed mammogram itself, the "quality" of the developed image and, accordingly, the extent to which the radiograph may be relied upon to indicate the absence of, or, conversely, to show the presence of "abnormal" findings.